Digital video streams typically represent video using a sequence of frames (i.e. still images). An increasing number of applications today make use of digital video stream encoding for purposes other than traditional moving pictures (such as movies and video clips). For example, screen capture and screen casting applications generally represent the output of a computer monitor over time as a digital video stream, irrespective of the specialized nature of the content of the monitor. To permit transmission of digital video streams while limiting bandwidth consumption, a number of video compression schemes have been devised.
One such scheme encodes a frame and uses motion vectors to predict spatial movement of portions of the frame in another frame. By encoding the motion vectors and the differences between the image data in portions in each frame, the bandwidth needed to encode the image data can be reduced.